Many jobs require the use of hand held paint spray guns. These include certain jobs in manufacturing and jobs in automotive refinishing shops, for example. When an operator is required to frequently use a spray gun over a long period of time, the operator may develop fatigue in the hand and wrist. Fatigue can be aggravated by repeated motions, such as by frequently squeezing the spray gun trigger with the same finger motion, by unbalanced forces on the hand and wrist, by the weight of the gun, and by the force required to operate the gun trigger.
Typically, paint spray guns are manufactured from metals such as aluminum, stainless steel and brass, which resist attack from the materials being sprayed and are durable when used in a commercial environment. Such materials are relatively heavy and consequently result in a relatively high gun weight. The most commonly used spray guns use air for liquid atomization. The atomization air may be either at a relatively high pressure or it may be a high volume low pressure (HVLP) air flow. Where high pressure air is supplied to the gun, a relative strong trigger return spring has been used to assure closure of the liquid and air valves. A typical prior art spray gun may require a force on the order of 6 pounds (2.7 Kg.) to squeeze the trigger.
Normally, at least the compressed air is supplied to the gun through a hose secured to the gun handle. The paint or other coating fluid also may be supplied through a hose secured to the gun handle or it may be supplied through a hose or a paint cup secured to the gun body near a nozzle. The entire weight of the gun, air hose and paint supply hose must be supported by the operator's hand and wrist. There has been no suitable way for transferring some of the weight, for example, directly onto the arm of the operator in place of the wrist. At best, the operator could reduce the torque exerted on the gun by the air and paint hoses by holding the hoses with his or her free hand. Further, while the gun may be somewhat balanced for spraying a vertical surface, it can be awkward and stressful to spray a horizontal surface, such as the top or hood of an automobile. This is due to the design of the prior art guns to be held only by a handle. When spraying a horizontal surface, the wrist and arm must be angled to aim the gun at the horizontal surface.